1. Field of the Invention
The present invention relates generally to a belt tensioning device and more specifically to a belt tensioning unit which can be readily mounted on a variety of different internal combustion engines or the like devices.
2. Description of the Prior Art
FIGS. 1 and 2 of the drawings show a previously proposed arrangement disclosed in Japanese Patent Application First Provisional Publication No. 58-121344 published on July 19, 1983. As shown, this arrangement is mounted on an engine cylinder block 1 and arranged to tension a so called "timing belt" 2 which operatively interconnects a cam shaft pulley 3 with a pulley 4 connected to one end of the engine crankshaft. The tensioning arrangement includes an idler pulley 5 which is rotatably mounted on an arm 6 which is pivotal about a support pivot or pin 7. A tensioner mechansim 8 is mounted on the cylinder block 1 independently of the arm 6. This mechanism includes a hollow piston 9 reciprocatively disposed in a cylinderical housing 10, a compression spring 11 which biases the piston 9 toward the arm 6 and a damper arrangement which includes a inner piston like element 12 which is abutted by spring 11. A stud 13 mounted on the arm abuts a shaped concavity formed on the outboard end of the hollow piston 9.
This arrangement has suffered from the drawback in that, as (a) the length of the timing belt, the position and diameter of the pulleys connected by the timing belt all tend to vary from one type of engine to another and (b) the arm and the tensioner are independently mounted on the engine block, considerable care must be exercised to ensure that tensioner 8 is correctly positioned with respect to the arm 6 and that the tensioner 8 exerts the appropriate force on the arm. This of course requires careful manual manipulation. The care that must be excercised when this operation is carried out is increased by the fact that the bolt holes 14 formed in the mounting brackets 15 formed on the cylindrical housing 10 are circular and do not permit ready angular adjustment of the device.